Volcano Watch

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

May 16, 2013

Risky actions at Kīlauea's ocean entry are cause for concern

Do not be misguided by the risky actions of this person (upper right), who is standing on an active lava delta that could collapse without warning, amidst a plume of superheated steam, hydrochloric acid, and tiny particles of volcanic glass. To avoid these ocean entry hazards, HVO advises staying at least 400 m (one-quarter mile) from where lava enters the sea. USGS photo, March 2013.

Most of us feel fortunate if we never go near a dangerous battlefield. Yet, dozens, if not hundreds, of people are knowinglyor unwittinglydoing just that every day on Kīlauea Volcano.

The 'battlefield' in question is the ocean entry, where, according to legend, Pele, Hawaiian deity of volcanoes, clashes with her sister, Nāmakaokahaʻi, Hawaiian deity of the sea. Stories of their encounters reflect the tumultuous interactions that occur when lava meets the sea.

The USGS Hawaiian Volcano Observatory (HVO) has repeatedly cautioned people about the hazards of ocean entries in previous "Volcano Watch" articles. But Hawaiʻi residents and visitorsas individuals and in groupscontinue to put themselves at risk by approaching Kīlauea's current ocean entry too closely, both by land and by sea.

A recent example is kayakers who paddled just feet from lava streaming into the ocean. Then, further risking their lives, they went ashore, walking across new land built by the ocean entry and scooping molten lava with their paddles. Their actions were unsafe and cause for grave concernnot to mention, culturally insensitive.

Because so many things could have gone awryinstantly and with disastrous resultsfor the kayakers and other risk-takers, HVO is again reminding folks that ocean entries are exceedingly hazardous areas.

Lava entering the sea builds a platform of new land known as a lava delta. This new land appears deceptively stable, but the veneer of lava on its surface hides a foundation of loose rubble. Consequently, lava deltas are extremely unstable, and they canand docollapse without warning. Kīlauea's largest delta collapse sent 17.8 hectares (44 acres) of new land plummeting into the ocean. But a collapse of only 1 sq m (1 square yard) can be deadly, if that's where you're standing.

When lava deltas collapse, the mix of lava and seawater generates steam-driven explosions that blast fragments of molten lava and blocks of hot rock hundreds of meters (yards)both inland and seaward. Rocks the size of a small file cabinet have been hurled 300 m (330 yards), with fist-sized rocks thrown as far as 400 m (one-quarter mile).

If you are on or near a lava delta when it collapses, you are in immediate peril. Imagine the land beneath your feet abruptly giving way, plunging you into a chaotic jumble of scalding seawater and rocky debris. Envision a wave, generated by tons of rock crashing into the sea, swamping kayaks and boats, engulfing swimmers and paddle-boarders, and wreaking havoc as it washes ashore. This could all happen.

Should anyone tell you that a lava delta collapse can be foreseen in time to move from harm's way, do not entrust your safety to that person. There is no way to know exactly when a collapse might occurand it's unlikely that you can outrun, outpaddle, or outswim the dangers. Past attempts to flee lava delta collapses have ended with serious injuries and death.

In addition to lava delta collapses, ocean entries pose myriad other hazards, described in detail on HVO's website (http://hvo.wr.usgs.gov/hazards/oceanentry/main.html).

For example, the white plume produced when lava enters the sea may look harmless, but it is a corrosive mixture of superheated steam, hydrochloric acid, and tiny particles of volcanic glassall to be avoided. Ocean waves washing over an active entry can send boiling seawater farther inland than expected, scalding anyone in its path.

Not surprisingly, people are drawn to the beauty of ocean entries. But, like moths to a flame, approaching too closely is risky. Based on decades of experience observing ocean entries and the consequences of lava delta collapses, HVO advises people to stay 400 m (one-quarter mile) away from where lava enters the sea.

To date, four deaths on Kīlauea have been related to ocean entry hazards. Given the recently observed disregard for these hazards, we fear that tragedy will strike again.

Last week's fatality was not directly related to the ocean entry. But it underscores the need to be fully prepared for a long, hot hike if you plan to trek across Kīlauea's lava flow field, which can be legally accessed via Hawaiʻi Volcanoes National Park. Tips for safe lava hiking and viewing are available online (http://pubs.usgs.gov/fs/2000/fs152-00/fs152-00.pdf) and from National Park rangers.

With due diligence, you can safely witness lava entering the sea. Know the hazards. Keep a safe distance from the ocean entry. And, above all, do not be misguided by the risky actions of others.

Kīlauea Activity Update

A lava lake within the Halemaʻumaʻu Overlook vent produced nighttime glow that was visible from the Jaggar Museum overlook and via HVO's Webcam during the past week. The lava lake reached to within 40 m (130 ft) of the floor of Halemaʻumaʻu Crater, in response to a several-day-long inflation, before cycles of deflation and inflation (DI events) started again in the afternoon on Monday, May 13. The lava level dropped thereafter, rising and falling between about 50 and 70 m (165230 ft) below the crater floor.

On Kīlauea's east rift zone, breakouts from the Peace Day tube remain active on the pali and on the coastal plain. Small ocean entries are active on both sides of the Hawaiʻi Volcanoes National Park boundary, though the entry within the National Park has diminished considerably. A breakout started on May 6 from a spatter cone on the northeast edge of Puʻu ʻŌʻō's crater floor has traveled about 1 km (0.6 miles) toward the north, adjacent to the Kahaualeʻa flow that died last month.

No earthquakes were reported felt in the past week across the Island of Hawaiʻi.